Serverless Adapters (s200/aws-lambda, s200/vercel)

AWS Lambda and Vercel invoke the app behind a platform-specific entry — these adapters build that entry from handle, so the same app deploys to either unchanged.

AWS Lambda (s200/aws-lambda)

For API Gateway HTTP APIs and Lambda function URLs — payload format v2 only (the REST API v1 event and its multiValueHeaders are not supported).

// src/lambda.ts
import { createLambdaHandler } from 's200/aws-lambda';
export const handler = createLambdaHandler(app);

Point the function at <file>.handler — a function URL or an HTTP API Lambda proxy integration both speak v2. createLambdaHandler(app) returns (event, context?) => Promise<LambdaResultV2>; the context parameter is accepted and ignored (the v2 result shape has no use for it). The event/result types (LambdaEventV2, LambdaResultV2, LambdaHandler) are exported and fully structural — no @types/aws-lambda dependency.

Event mapping

Event field (v2)	Request side
requestContext.http.method	request method
headers (v2 lowercases names)	request headers
cookies	joined with "; " into one Cookie header
host header	URL host (https:// scheme; a host outside the authority grammar, or one the URL parser rejects, falls back to localhost)
rawPath / rawQueryString	URL path and query, passed through un-re-encoded
body + isBase64Encoded	request body — base64-decoded when flagged; an absent, null or empty body means no body, and a body on GET/HEAD is dropped (a Request rejects one)

Only the fields above are read — routeKey, version, and the rest of requestContext pass through unused.

Result mapping

Response	Result field (v2)
status	statusCode
each Set-Cookie	one cookies array entry — never merged into headers
other headers (duplicates merged with ", ")	flat headers record
textual body	body string, isBase64Encoded: false
any other body	base64 body, isBase64Encoded: true
null body (204/304, …)	no body

Textual means text/*, JSON (including +json suffixes), JavaScript, XML (including +xml), and application/x-www-form-urlencoded — plus an absent content-type. Any content-encoding other than identity forces base64: the compress battery's gzip turns text types binary.

onFinish callbacks run when the adapter finishes buffering the result — { aborted: false }, unless the response body itself failed mid-read ({ aborted: true }, and the error rethrows for the runtime to report).

Vercel (s200/vercel)

Both the Edge Runtime and Node.js — including Fluid Compute — use the plain Web Standard handler shape:

// api/index.ts
import { createVercelHandler } from 's200/vercel';
export default createVercelHandler(app);

createVercelHandler(app) → (request: Request) => Promise<Response> — handle under the platform's entry name, carrying the same wiring as the other edge adapters: the runtime's request signal (client disconnect on the Edge Runtime) threads into ctx.signal via feature detection, and onFinish callbacks ride the response body — cancel → { aborted: true }, completion → { aborted: false }, exactly once.

For the Edge Runtime, opt the route in with export const config = { runtime: 'edge' };. Node.js needs nothing — it is the default runtime.

Limitations

• Lambda: payload v2 only — the REST API v1 event and multiValueHeaders are not translated (use an HTTP API or function URL).
• Connection upgrades (s200/websocket) need a long-lived socket, which serverless platforms do not offer — the upgrade path is unreachable on both adapters.